<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    div{
      width: 500px;
      height: 360px;
      border: 1px solid red;
    }
    #d1{
   /*   margin-left: 50px;
      margin-top: 100px;
      margin-right: 50px;!*没有效果*!
      margin-bottom:100px ;
*/
      background-image:url("j.jpg") ;
      /*四个方向赋值*/
      margin: 50px;
      /*上下和左右赋值*/
      margin: 50px 100px;
      /*上右下左顺时针赋值*/
      margin: 10px 20px 30px 40px;
    }
    #d2{
      /*上下相邻的两个元素彼此添加外边距，取最大值*/
      margin-top:50px ;
    }
    #s1{
      margin-right: 100px;
      /*行内元素上下外边距无效*/
      margin-bottom: 100px ;
    }
    #s2{
      /*左右相邻元素彼此添加外边距  求和*/
      margin-left: 50px;
    }
  </style>
</head>
<body>
<span id="s1">span1</span>
<span id="s2">span2</span>


<div id="d1">div1</div>
<div id="d2">div2</div>

</body>
</html>